Container closure



2 Sheets-Sheet l H. B. EGLESTON AL CONTAINER CLOSURE Oct. 22, 1968 Filed March 17; 1966 INVENTOR ARRY B.EGL.E.STON

. FELIKS ATTORNEY Oct. 22, 1968 a LESTON ET AL 3,406,892

CONTAINER CLOSURE Filed fiarch 17. 1966 2 Sheets-Sheet 2 INVENTORS HARRY B.EGL.ESTON JAMES J. FELIKS Ian-.04. 46m

ATTORNEY United States Patent O 3,406,892 CONTAINER CLOSURE Harry B. Egleston, Livonia, and James J. Feliks, Walled Lake, Mich., assignors to Ex-Cell-O Corporation Filed Mar. 17, 1966, Ser. No. 535,241 6 Claims. (Cl. 229-37) ABSTRACT OF THE DISCLOSURE A liquid tight container bottom closure formed from a thermoplastic sheet material that can be folded and heat sealed by automatic equipment.

In the packaging of fluids, extensive use has been made of containers formed of paperboard having an overall coating of thermoplastic film, such as polyethylene, applied on both surfaces of the board. One form of a container of this type just noted and presently in wide commercial use is disclosed in US. Patent 3,120,335, issued Feb. 4, 1964.

Although plastic coated containers of the above described type have been commercially successful, there are certain disadvantages in their use, one of the most serious of which involves the exposure of certain of the raw or cut edges of the blank, when formed into a container, to the product. The result is that a liquid product penetrates by a wicking action into the exposed paperboard, with a resultant weakening of the board and eventually failure of the container. Another disadvantage of the present plastic coated container results from the effect of continuous vibration during extended transportation, which can cause a failure of the container bottom by the thin plastic coating developing fatigue cracks. As a conse quence, various cost increasing measures, such the employment of foil or other intermediate barrier layers, and blocking or coating the exposed raw edges, are required to insure a fluid-tight transportable container having substantial shelf life.

It is, therefore, one object of the present invention to provide a container fold-in closure formed from a thermoplastic sheet material that can be effectively heatsealed.

A further object of the invention is to provide a new and improved liquid-proof container bottom closure formed of thermoplastic sheet material which will be strong, simple to erect, close and seal, and susceptible of high volume economical machine production for packaging liquid products.

Still another object is the provision of a novel container bottom closure construction having its fold-in panels so designed that they can be automatically closed and heat-sealed wherein the flow pattern of Weld material is confined within the peripheral limits of the container.

A still further object of the invention is the provision of a container bottom closure construction wherein no more than two surfaces are required to he heat-sealed together at any one location to attain a liquid-tight seal.

Another object of this invention is the provision of a fold-in container bottom closure construction having a minimum of material.

Other objects and advantages of the present invention will become apparent as the following description proceeds, taken in connection with the accompanying drawings, wherein:

FIG. 1 is a layout view of a portion of a container blank from which the closure of the instant invention is formed showing the outside surface thereof.

FIG. 1A is an enlarged view of the portion of FIG. 1 within the dashed circle.

FIG. 2 is a perspective view of container showing the bottom end the blank of FIG. 1.

FIG. 3 is a plan view of the container bottom of FIG. 2.

FIG. 3A is an enlarged cross section taken on the line 3A3A of FIG. 3.

FIGS. 4, 5 and 6 are fragmentary perspective views illustrating, sequentially, various steps in forming the bottom closure of the container of FIG. 2.

FIG. 7 is a plan view of the closure as viewed in FIG. 6.

Referring now to the drawings, FIG. 2 generally indicates a thermoplastic container C having a bottom closure made in accordance with the principle of the present invention. The container described in this application is made from high density polyethylene, but it should be understood that other suitable thermoplasic sheet material, such as polyvinyl chloride, polyvinyl acetate, vinyl copolymers, polypropylene, polystyrene, cellulose acetate and cellulose acetate butyrate may be employed without departing from the spirit and scope of the invention.

Referring more specifically to FIG. 1, the container bottom is shown as a fragmentary blank 10 with a pattern of appropriate score lines and having the outside surface of the blank showing. The bottom closure layout of FIG. 1 is adapted to be erected into the completed container closure of FIG. 2. The container C includes a tubular body 11, which in the present instance is of substantially square cross-section. One end of the body 11 is provided with a suitable top closure 12 which may, for example, be of the familiar gable top end closure as disclosed in copending application of Harry B. Egleston, Ser. No. 534,257 filed Ian. 6, 1966, the details of which are of no concern here.

The flat bottom closure 13 is shaped from the blank of FIG. 1, which is separated into two groups of panels by a staggered score line generally indicated at 14. The material above score line 14 is the bottom closure group, While the portion below the score line 14 is the body group and comprises four panels 15-18. The body group is defined with the panels being separated by score lines 1923.

It will be noted that each of the side seam panels 24, 25 extend longitudinally the entire height of blank 10 in the same manner as a conventional side seam flap as shown, for example, in the copending [application of Elwyn R. Gooding, Ser. No. 474,869, filed July 26, 1965, now Patent No. 3,334,802. In the present embodiment of the invention, the container C is formed by first being side seamed. This can be accomplished by having panels 15 and 16, and flap 24, folded about score line 21 until their inside surfaces contact the inside surfaces of panels 18, 17 land flap 25 respectively. The coincident side edges formed by scores 19 and 23 of the panels 15 and 18 can be simultaneously cut from their associated flaps 24 and 25 and heat-sealed by the use of a hot knife or radiant hot wire to form a side seam. The blank 10 is then opened into tubular form, substantially square in cross section as seen in FIG. 4. I

It is to be understood that applicants invention is not limited to any-particular method of side seaming; and other methods using separate cutting and heat sealing operations could be employed. The sealing phase could be accomplished by other heating methods, such as rotarytype continuous heat bar sealers or impulse sealers. Also, the utilization of ultrasonic infra-red and dielectric sealing methods are within the contemplation of the instant invention.

While applicants bottom closure is preferably formed from a blank that has been edge-sealed without any overan inverted gable top closure erected from 0. lap, other arrangements, such as a form of the conventional side seam flap utilized, for example, in plastic coated cartons of the type shown in U.S. Patent 3,120,335, could be used and still embody the principles of the invention.

As can be seen in FIG. 1, the alternate side panels 16, 18 have respectively connected therewith substantially trapezoidal shaped major extension panels 26, 27. These major panels are joined along their larger bases at individual score lines 30, 31 to their respective side panels 16, 18. Each of the trapezoidal extension panels 26, 27 is flanked at its sides along respective angular score lines 32, 33 and 34, 35 by a plurality of triangular corner rib panels 36, 37 and 38, 39.

The alternate side panels 15, 17 have respectively connected therewith substantially trapezoidal shaped minor extension panels 28, 29. These minor extension panels are joined along their larger bases by individual score lines 40, 41 to their respective side panels 15, 17. Each of the trapezoidal minor panels is flanked on its sides along respective pairs of angular score lines 42, 43 and 44, 45 by trapezium shaped panels 46, 47 and 48, 49.

Thus, the triangular panel 36 and the trapezium panel 47 are hinged together along score line the panels 37, 48 are hinged together along score line 21, while the panels 38, 49 are hinged together along score line 22. The panels 39, 46 are hinged together along the previously discussed side seams generally referred to as thermo-fused joint 57, as viewed in FIGURE 4, formed at the juncture of the blank scores 19 and 23. It will be noted in FIG. 1 that the extension of the scores 20, 21 and 22 to the upper edge of the blank 10 is accomplished for the convenience of forming the tube of FIG. 4 on a machine mandrel, and they are not utilized during the fold-in sequence shown in FIGS. 5 and 6. p

The angular score lines 32, 33, 34, are disposed relative to the longitudinal scores 20, 21, 22, 23 respectively, the angle being delineated by the letter A in FIG. 1A for the score 34. In the instant embodiment, the angle A is approximately 22 /2 and its complementary angle of 67 /2 is shown at D. It will be noted in the enlarged FIG. 1A that the score line 34 intersects the horizontal score 31 substantially at its juncture with the vertical score line 22.

The score lines 42, 43, 44, are angularly disposed relative to longitudinal scores 19, 20, 21, 22 respectively, the angle being delineated by the letter A. In the instant embodiment the angle A is again approximately 22 /2 so that the sum of angles A and A, represented by the letter B, is 45". It will similarly be noted in enlarged FIG. 1A that the horizontal score line 41 intersects the score line 45 substantially at its juncture with the vertical score line 22. The vertical offset between individual staggered scores 31 and 41 will vary, depending upon the thickness of the sheet plastic used for various size containers. For example, applicants one-half pint container, using a sheet material of approximately 15 mils, will provide an offset within the range of & inch. The purpose of this staggered scoring is to accommodate the thickness of the plastic as it is formed along the score lines when the container is erected, and thus prevent crowding of the plastic at the various corner junctions of the score lines.

The panels 26, 27 are mirror images of each other and have corresponding pairs of free edges 50 and 52 which are angularly disposed relative to the vertical, the angle being approximately 45 and indicated at E in FIG. 1. It will be noted that the pairs of edges 50 and 52 intersect the horizontal free edges 53 of blank 10 at points such that their length, represented by the Letter Z, is less than the width of the body panels 15-18 indicated generally by the dimension W. The portions 53' of each edge 53 are equal in length and form the fourth leg 46, 47, 48, 49 of the trapezium fold-back panels of the completed closure 13. The minor panels 28, 29 are similarly mirror images of each other and have a height dimension represented at X which is approximately one-quarter the panel dimension W.

In the case of major panels 26, 27 it will be observed that they are cut and scored essentially in a trapezoidal configuration. The major panel 26 has an extended tuck-in flap S4 and major panel 27 has an extended overlying or outside overlap flap 55. The end portions of the flaps 54, 55 are relieved or chamfered at 56 for ease of infolding. While the angle of chamfer is shown as being 45 to agree with the angle E of edge pairs 50 and 52, it will be observed that the flap edges could be formed at various angles.

When the container C is assembled from the blank 10, the panel edges 19 and 23 are joined together along the thermofused joint 57 in a manner such as described above and erected into a tube of substantially square cross section (FIG. 4). The manner in which the bottom panels close the container is shown in FIGS. 5 and.6. Together, the major panels 26, 27 are folded inward toward each other. The folding occurs at the lateral scores 30, 31 and the folding scores 32, 33, 34 and 35. In turn, the minor panels 28, 29 are moved towards each other. This causes the generally trapezium shaped foldback member (bounded by the scores 45, 34 and the free edges 52 and 53) constituting the individual panel members 38, 49 to rotate around score line 45 so that the inside surfaces of member 38, 49 and panel 29 are brought together. At the same time and during the same movement member 38, 49 is rotating around score line 34, thus the outside surfaces of member 38, 49 and panel 27 are brought together. Fold-back members 36, 47; 37, 48; and 39, 46 make the same movements as member 38, 49 with panels 28-26, 29-26 and 28-27 respectively. Bottom closure major panel 26 moves towards bottom closure major panel 27 just enough faster than panel 27 moves towards panel 26 so that tuckin flap 54 is positioned beneath overlap flap 55. FIG. 6 shows the bottom when completely closed preparatory to being heat sealed.

It has been the practice with prior foldin bottom arrangements to require a preheat of the closure panels before they are finally folded or sealed because of the superimposed three or more layers of closure folds. This is because with moderate heating temperatures layers consisting of two-ply become welded, but greater multiple layers do not. By increasing the heating temperature, multiple layers can be welded but may, as a result of the increased temperature to which the thermoplastic is submitted, develop pimpled deformations, or even fuse altogether so that holes appear in the packaging envelope.

In the instant invention, only when the bottom closure is completed, as viewed in FIG. 6, is it subjected to pressure and heat. The enlarged FIG. 7 indicates the substantially parallel relationship between free edges 50, 52 and their associated minor panel edge 53, which is offset therefrom by an amount indicated by the letter F. As shown in FIG. 3, the end of minor panel 29 is fused to the outer surface of major panels 26, 27 by heat seal 58; the ends of panels 38, 49 and 37, 48 are fused to the inner surface of panel 29 by heat seals 59 and 60, respectively, and the free edges of the flaps 54, 55 are fused to the inner and outer surfaces of the panels 27 and 26 by heat seals 61 and 62 respectively, thus forming a liquidtight closure. As the heat seal pattern (FIG. 3) is identical for the right half of the closure only, the seals on the left half have been shown. The closure of the instant embodiment was madeby subjecting the above mentioned superimposed portions of the thermoplastic material to a temperature of about 225 F. to 250 F. for about one second.

An advantage of applicants closure design is that the overlying panels may be heat-pressure sealed by a heating element or die having a generally I-I-shaped design corresponding generally to the outline shape of the zone 63 in FIG. 3. By virtue of this design a controlled zone of heat can be applied, together with pressure to cause the plastic material to flow in the regions of zone 63. The ability of applicants to attain a sound weld results from the closure design which requires only the outer two layers of sheet material depth to be welded together at any single location. As a result, a constant heat amount can be transmitted to the entire zone 63 for simultaneously thermofusing all of applicants closure lapseals, such that all the seals have approximately the same shear strength. Further, the foldin closure 13 is not only formed using a minimal amount of material, but the heat zone 63 insures that there will be no objectional overhang of fused mate rial after the heat sealing operation.

An example of sizes and dimensions that could be used would be a liquid half-pint container having a width of panel 16, the distance from the middle of score line 20 to the middle of score line 21, of 2.764 inches and all other panels 15, 17 and 18' equal to panel 16. The distances from the middle of score line 30 to the edge 51 being 1.500 inches and the distance from the middle of score line 40 to the edge 53 being .688 inch. The height of the panels 16 and 18 being 1.875 inches, while the height of panels 15 and 17 will be .062 of an inch greater due to the equal offsets of .031 of an inch of their horizontal scores at each end.

As is evident from the foregoing discussion, the container closure of this invention may be also used with polymeric material in the form of a seamless tube, as well as two separate sheets having, for example, two thermofused joints coextensive with opposite corners such as 21 and 57 of FIG. 4.

While the invention is susceptible of various modifications and alternative constructions, a certain illustrative container closure has been shown in the drawings and described above in detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed. On the contrary, the intention is to cover all modifications, alternative constructions, equivalents and uses falling within the spirit and scope of the invention as expressed in the appended claims.

We claim:

1. A bottom end closure for a tubular container made from thermoplastic sheet material having,

(a) a tubular body defined by four substantially rectangular side walls,

(b) said bottom end closure connected to and extending from said side walls,

(0) said bottom end closure having first and second major panels extending from two opposed side walls,

(d) said bottom end closure having first and second minor panels extending from the two remaining opposed side walls,

(e) a pair of trapezium panels connected to each of said minor panels,

(f) a pair of triangular corner rib panels connected to each of said major panels,

(g) each of said triangular corner rib panels is connected to one of said trapezium panels,

(h) said major and minor panels extend over the bottom end of said container,

(i) at least one of said major panels extend over one half of the distance across the bottom end of said container,

(j) said minor panels extend less than one half the distance across the bottom end of said container,

(k) said triangular corner rib panels and said connected trapezium panels form a co-planar surface positioned between the major and minor panels and the edges of the co-planar surfaces are positioned a predetermined distance from the end edge of said minor panels,

(1) first and second heat seals are placed along the ends of said major panel welding its end to the other major panel,

seal to form -a liquid tight bottom end closure. 2. A bottom end closure according to claim 1, wherein:

(a) said edges of the co-planar surfaces are positioned between the end edge of said minor panel they are connected with and the side is connected to. 3. A bottom end closure according to claim 1, wherein:

(a) said major and minor panels are connected to and extend completely across the ends of their side walls along a substantially straight first score line,

(b) said major panels are provided with a pair of substantially straight angular second score lines formwall said minor panel ing substantially at side edges of said side walls and extending inwardly,

(c) four substantially straight parallel third side score lines forming the side edges of said side walls and extend to the free edges of said bottom end closure,

(d) said third score lines are substantially perpendicular to said first score line,

(e) one of said third score lines and one of said angular second score lines on said major panels form one of said triangular corner rib panels with the free edge of said bottom end closure,

(f) said minor panels are provided with a pair of substantially straight fourth angular minor panel score lines forming acute angles with said first score line and starting substantially at side edges of said side walls and extending inwardly,

(g) one of said third score lines and one of said fourth angular minor panel score lines form one of said trapezium panels on said minor panels with the free edge of said bottom end closure, and

(h) one of said connected trapezium panels and one of said triangular corner rib panels acting with a common third side score lines form one of said of said co-planar surfaces.

4. A bottom end closure according to claim 3, where- (a) said free edge of said bottom end closure has a first edge as one edge of said trapezium panel and a second edge as one edge of said triangular corner rib panel, and

(b) said first edge and said second edge intersect between said fourth angular minor panel score line and its adjacent third score line.

5. A blank for a container made of thermoplastic 0 material comprising:

(a) a top closure group, a side wall panel group,

(b) a first score line dividing said bottom closure group from said wall panel group, said first score .line extending for the full width of said blank,

(c) a second panel score line, a third panel score line and a fourth panel score line dividing said wall panel group into four panels, said second, third and fourth panel score lines being substantially perpendicular to said first score line extending the full height of said blank,

(d) said second, third and fourth side panel scores dividing said bottom closure group into pairs of major and minor bottom closure panels alternately connected to the wall panels as extensions thereof,

a bottom closure group and ing acute angles with said first score line and start-- (e) said major and minor panels connected to their adjacent wall panel at said first score line and have a free edge away from said first score line,

(f) said major panels having a pair of corresponding triangular corner rib panels,

(g) each of said triangular corner rib panels having one side formed by one side of a major panel, a second side formed by one of said panel score lines, and a third side by a free edge,

(h) said minor panels having a pair of corresponding trapezium panels,

(i) Each of said trapezium panels having one said formed by one side of minor panel, a second side formed by a wall panel score line, a third side in alignment with the free edge of the adjacent triangular corner rib panel, and a fourth side in alignment with the free edge of its adjacent minor panel,

(j) said free edge of a minor panel is substantially parallel to said first score line and is a distance from it less than one half the width of its adjacent wall panel, and

(k) said free edges of said major panels are substantially parallel to said first score line and at least one is a distance from it equally more than one half the width of its adjacent wall panel.

A 6. A blank for a container according to claim 5, wherein' (a) the instersection of said third side and said fourth side of a trapezium is between its said one side and said second side.

References Cited 20 DAVID M. BOCKENEK, Primary Examiner. 

